require 'digest/sha1'

class Student < ActiveRecord::Base
   validates_presence_of     :account, :password
   validates_uniqueness_of   :account
 
#  attr_accessor :password
  attr_accessor :password_confirmation
  validates_confirmation_of :password

  def validate
    errors.add_to_base("Missing password") if hashed_password.blank?
  end
  
  def self.authenticate(account, password)
    student = self.find_by_account(account)
    if student
      expected_password = encrypted_password(password, student.salt)
      if student.hashed_password != expected_password
        student = nil
      end
    end
    student
  end

  
  def password
    @password
  end
  
  def password=(pwd)
    @password = pwd
    return if pwd.blank?
    create_new_salt
    self.hashed_password = Student.encrypted_password(self.password, self.salt)
  end
  
  def after_destroy
    if Student.count.zero?
      raise "Can't delete last student"
    end
  end     
  
  private  
  def create_new_salt
    self.salt = self.object_id.to_s + rand.to_s
  end
  
  def self.encrypted_password(password, salt)
    string_to_hash = password + "wibble" + salt
    Digest::SHA1.hexdigest(string_to_hash)
  end
end
